Organic electroluminescent element and display medium

ABSTRACT

An organic electroluminescent element includes a pair of electrodes formed of a positive electrode and a negative electrode, with at least one of the electrodes being transparent or semi-transparent, and one or more organic compound layers interposed between the pair of electrodes, with at least one layer containing one or more charge transporting polyesters represented by the following formula (I), wherein A 1  represents at least one selected from structures represented by the following formula (II), and X represents a group represented by the following formula (III):

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2011-168827 filed Aug. 1, 2011.

BACKGROUND

1. Technical Field

The present invention relates to an organic electroluminescent element and a display medium.

2. Related Art

Electroluminescent elements are self-luminescent, all-solid elements. Research on electroluminescent elements using organic compounds has been started initially by using single crystals of anthracene or the like.

The light emission of these elements is a phenomenon in which, when electrons are injected from one of the electrodes, and holes are injected from the other electrode, the luminescent material in the electroluminescent element is excited to a higher energy level, and the excessive energy occurring when the excited luminescent body returns to the ground state, is emitted as light.

In regard to organic electroluminescent elements, research and development has been conducted in recent years also on electroluminescent elements which use polymer materials instead of low molecular weight compounds.

SUMMARY

According to an aspect of the present invention, there is provided an organic electroluminescent element including:

a pair of electrodes including a positive electrode and a negative electrode, at least one of the electrodes being transparent or semi-transparent; and

one or more organic compound layers interposed between the pair of electrodes, with at least one layer containing one or more charge transporting polyesters represented by the following formula (I):

wherein in the formula (I), A¹ represents at least one selected from structures represented by the following formula (II); Y¹s each independently represent a substituted or unsubstituted divalent hydrocarbon group; m's each independently represent an integer of from 1 to 5; p represents an integer of from 5 to 5,000; R¹s each independently represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

wherein in the formula (II), Ar's each independently represent a substituted or unsubstituted phenyl group, a substituted or unsubstituted monovalent polynuclear aromatic hydrocarbon group having two aromatic rings, a substituted or unsubstituted monovalent condensed aromatic hydrocarbon group having two or three aromatic rings, or a substituted or unsubstituted monovalent aromatic heterocyclic group; j's each independently represent 0 or 1; T's each independently represent a divalent linear hydrocarbon group having from 1 to 6 carbon atoms, or a divalent branched hydrocarbon group having from 2 to 10 carbon atoms; and X represents a group represented by the following formula (III):

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:

FIG. 1 is a schematic configuration diagram showing the layer configuration of an organic electroluminescent element according to an exemplary embodiment of the present invention;

FIG. 2 is a schematic configuration diagram showing the layer configuration of an organic electroluminescent element according to another exemplary embodiment of the present invention;

FIG. 3 is a schematic configuration diagram showing the layer configuration of an organic electroluminescent element according to another exemplary embodiment of the present invention; and

FIG. 4 is a schematic configuration diagram showing the layer configuration of an organic electroluminescent element according to another exemplary embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, an exemplary embodiment of the present invention will be described in detail.

<Organic Electroluminescent Element>

The organic electroluminescent element (hereinafter, may be referred to as “organic EL element”) of the exemplary embodiment of the present invention includes a pair of electrodes including a positive electrode and a negative electrode, at least one of the electrodes being transparent or semi-transparent, and one or more organic compound layers interposed between the pair of electrodes, with at least one layer containing one or more charge transporting polyesters represented by formula (I):

In formula (I), A¹ represents at least one selected from structures represented by formula (II); Y¹s each independently represent a substituted or unsubstituted divalent hydrocarbon group; m's each independently represent an integer of from 1 to 5; p represents an integer of from 5 to 5,000; and R¹s each independently represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

In formula (II), Ar's each independently represent a substituted or unsubstituted phenyl group, a substituted or unsubstituted monovalent polynuclear aromatic hydrocarbon group having two aromatic rings, a substituted or unsubstituted monovalent condensed aromatic hydrocarbon group having two or three aromatic rings, or a substituted or unsubstituted monovalent aromatic heterocyclic group; j's each independently represent 0 or 1; T's each independently represent a divalent linear hydrocarbon group having from 1 to 6 carbon atoms, or a divalent branched hydrocarbon group having from 2 to 10 carbon atoms; and X represents a group represented by formula (III):

In regard to the charge transporting polyester according to the exemplary embodiment of the present invention, it is speculated that when a dibenzothiophene ring linked to a phenylene group is included in the molecular structure, the ionization potential is controlled to a low level, and therefore, the charge injectability from the electrode is improved. Furthermore, the structure containing a dibenzothiophene ring linked to a phenylene group described above has excellent solubility and compatibility with solvents or resins. Therefore, it is speculated that when the above-described charge transporting polyester is used, the element becomes large-area, and organic electroluminescent elements may be easily produced.

Furthermore, the charge transporting polyester is such that by selecting the structure that will be described later, the polyester may be imparted with any function of hole transport capability and electron transport capability, and therefore, the polyester is used in any of a hole transport layer, alight emitting layer, an electron transport layer and the like according to the purpose. In addition, since the charge transporting polyester according to the exemplary embodiment of the present invention has a relatively high glass transition temperature and a large degree of charge mobility, it is speculated that current can flow easily, an increase in the voltage is suppressed, heat is not easily generated during light emission, so that the polyester has excellent stability, and has a lengthened element service life.

Also, according to the exemplary embodiment of the present invention, the term “charge transporting polyester” means a polyester which is a semiconductor capable of transporting holes or electrons as charges.

(Charge Transporting Polyester)

Hereinafter, the charge transporting polyester according to the exemplary embodiment of the present invention will be described in detail. First, the structure of A¹ in the formula (I), which is a feature of the charge transporting polyester, will be explained.

In formula (II), Ar's each independently represent a substituted or unsubstituted phenyl group, a substituted or unsubstituted monovalent polynuclear aromatic hydrocarbon group having two aromatic rings, a substituted or unsubstituted monovalent condensed aromatic hydrocarbon having two or three aromatic rings, or a substituted or unsubstituted monovalent aromatic heterocyclic group. Meanwhile, the two Ar's present in the formula (II) may be identical with or different from each other, but when two Ar's are identical, production is facilitated.

Here, the polynuclear aromatic hydrocarbon group and the condensed aromatic hydrocarbon group according to the exemplary embodiment of the present invention specifically mean groups having polycyclic aromatic rings defined below (that is, a polynuclear aromatic hydrocarbon or condensed aromatic hydrocarbon).

That is, the term “polynuclear aromatic hydrocarbon” means a hydrocarbon in which two or more aromatic rings each composed of carbon and hydrogen are present, and the rings are bonded through carbon-carbon bonding. Specific examples include biphenyl. Furthermore, the term “condensed aromatic hydrocarbon” means a hydrocarbon compound in which two or more aromatic rings are each composed of carbon and hydrogen, and these aromatic rings share a pair of carbon atoms that are adjacently bonded. Specific examples include naphthalene, anthracene, phenanthrene, and fluorene.

Furthermore, according to the exemplary embodiment of the present invention, the aromatic heterocyclic group selected as a structure representing Ar in the formula (II) means a group having an aromatic heterocyclic ring defined below.

That is, the term “aromatic heterocyclic ring” means an aromatic ring which also contains elements other than carbon and hydrogen, and for example, compounds in which the number of atoms (Nr) constituting the ring skeleton is at least any one of 5 and 6. Furthermore, the type and number of atoms other than the carbon atoms constituting the ring skeleton (heteroatoms) are not particularly limited, but for example, a sulfur atom, a nitrogen atom, an oxygen atom and the like are used. Thus, the ring skeleton may contain at least any of two or more kinds of heteroatoms and two or more heteroatoms. Particularly, as a heterocyclic ring having a 5-membered ring structure, for example, thiophene, pyrrole, furan, and heterocyclic rings in which the carbon at the 3-position and the 4-position of the above-described compounds are substituted with nitrogen, are used, and as a heterocyclic ring having a 6-membered ring structure, for example, pyridine is used.

Furthermore, it is desirable that the aromatic heterocyclic group have the aromatic heterocyclic ring described above, and the aromatic heterocyclic group contain, in addition to the group constituted of the aromatic heterocyclic ring, both a group in which an aromatic ring is substituted with the aromatic heterocyclic ring, and a group in which the aromatic heterocyclic ring is substituted with an aromatic ring. Specific examples of the aromatic ring include those aromatic rings described above.

That is, the aromatic heterocyclic group may be, for example, a group of the polycyclic aromatic ring described above (that is, a monovalent polynuclear aromatic hydrocarbon having two or more aromatic rings, or a monovalent condensed aromatic hydrocarbon having two or more aromatic rings), in which one or more aromatic rings are substituted with an aromatic heterocyclic ring, and specific examples include a thiophenylphenyl group, a phenylpyridine group, and a phenylpyrrole group.

In formula (II), examples of the substituent used to further substitute the phenyl group, polynuclear aromatic hydrocarbon group, condensed aromatic hydrocarbon group and aromatic heterocyclic group that are represented by Ar, include a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, a substituted amino group, and a halogen atom.

The alkyl group may be, for example, an alkyl group having from 1 to 10 carbon atoms, and examples include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

The alkoxy group may be, for example, an alkoxy group having from 1 to 10 carbon atoms, and examples include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group.

The aryl group may be, for example, an aryl group having from 6 to 20 carbon atoms, and examples include a phenyl group and a toluoyl group.

The aralkyl group may be, for example, an aralkyl group having from 7 to 20 carbon atoms, and examples include a benzyl group and a phenethyl group.

Examples of the substituent of the substituted amino group include an alkyl group, an aryl group and an aralkyl group, and specific examples are as described above.

In formula (II), T's each independently represent a divalent linear hydrocarbon group having from 1 to 6 carbon atoms, or a divalent branched hydrocarbon group having from 2 to 10 carbon atoms, and among them, examples include a divalent linear hydrocarbon group having from 2 to 6 carbon atoms and a divalent branched hydrocarbon group having from 3 to 7 carbon atoms. Among these, more specific examples include, in particular, divalent hydrocarbon groups shown below.

In formula (II), j's each independently represent 0 or 1.

In addition, T and j that are respectively present twice in the formula (II), may be identical with or different from each other, but when the two are identical, the production of the charge transporting polyester is much easier.

The at least one selected from the structures represented by the formula (II) explained above is A¹ in the charge transporting polyester represented by formula (I).

In addition, the plural A¹s present in the charge transporting polyester represented by the formula (I) may have the same structure or may have different structures.

In the formula (I), Y¹s each independently represent a substituted or unsubstituted divalent hydrocarbon group. The divalent hydrocarbon group represented by Y¹ is a divalent alcohol residue, and examples include an alkylene group, a (poly)ethyleneoxy group, a (poly)propyleneoxy group, an arylene group, a divalent heterocyclic group and combinations thereof. The carbon number of the divalent hydrocarbon group represented by Y¹ may be, for example, in the range of from 1 to 18, and the carbon number may also be in the range of from 1 to 6.

That is, specific examples of the divalent hydrocarbon group represented by Y¹ include an alkylene group having from 1 to 10 carbon atoms, and an arylene group having from 6 to 18 carbon atoms, and the divalent hydrocarbon group may also be an alkylene group having from 1 to 5 carbon atoms.

Specific examples of Y¹ include groups selected from among the following formulas (IV-1) to (IV-8).

Meanwhile, the plural Y¹s present in the charge transporting polyester represented by the formula (I) may be identical with or different from each other.

In the formulas (IV-1), (IV-2), (IV-5) and (IV-6), R³ and R⁴ each represent a hydrogen atom, a substituted or unsubstituted alkyl group having from 1 to 4 carbon atoms, a substituted or unsubstituted alkoxy group having from 1 to 4 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, or a halogen atom; a, b and c each independently represent an integer of from 1 to 10; e represents an integer of from 0 to 2; d and f represent 0 or 1; and V represents a group represented by the following formulas (V-1) to (V-12)

In the formulas (V-1), (V-10), (V-11) and (V-12), represents an integer of from 1 to 20; and h represents an integer of from 0 to 10.

In the formula (I), m's each independently represent an integer of from 1 to 5, and the plural m's present in the charge transporting polyester represented by the formula (I) may be identical with or different from each other.

In the formula (I), R's each independently represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group. Specific examples of the alkyl group, aryl group and aralkyl group as well as the substituents substituting these groups are the same as the specific examples mentioned as the substituents substituting the aromatic ring of Ar.

Furthermore, in the formula (I), R¹ may be a hydrogen atom or a phenyl group among the examples described above, and from the viewpoints of cost reduction and the ease of production, R¹ may be a hydrogen atom. Two R¹s in the formula (I) may be identical with or different from each other, but when the two are identical, the production of the charge transporting polyester is much easier.

In the formula (I), p represents an integer of from 5 to 5,000, but may also be in the range of from 10 to 1000.

More specifically, the weight average molecular weight Mw of the charge transporting polyester may be, for example, in the range of from 5,000 to 300,000, and may also be in the range of from 10,000 to 100,000.

The weight average molecular weight Mw is measured by the following method. That is, the weight average molecular weight is measured by preparing a 1.0% by mass tetrahydrofuran solution of the charge transporting polyester, and performing gel permeation chromatography (GPC) using a differential refractive index detector (RI) and using styrene polymers as standard samples.

Furthermore, the glass transition temperature (Tg) of the charge transporting polyester may be, for example, from 60° C. to 300° C., and may also be from 100° C. to 200° C.

Meanwhile, the glass transition temperature is measured with a differential scanning calorimeter using α-Al₂O₃ as a reference, by increasing the temperature of the sample to a rubbery state, immersing the sample in liquid nitrogen to quench the sample, and then increasing the temperature of the sample again under the conditions of a rate of temperature increase of 10° C./min.

The charge transporting polyester represented by the formula (I) is synthesized by, for example, polymerizing a charge transporting monomer represented by the following structural formula (VI) by a known method described in, for example, “Lectures on Experimental Chemistry, 4^(th) Edition”, Vol. 28 (edited by the Chemical Society of Japan, Maruzen Co., Ltd., 1992) or the like.

In the formula (VI), Ar, X, T and j are the same as Ar, X, T and j defined for formula (II), respectively. In the formula (VI), A² represents a hydroxyl group, a halogen atom, or —O—R⁵ (wherein R⁵ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group).

Here, specific examples of the structure represented by formula (VI) are shown in Table 1 to Table 3. In the following, for each of the specific examples of the charge transporting monomer designated with a compound number (structure number) in Tables 1 to 3, for example, a specific example designated with number 5 will be denoted as “Monomer compound (5)”.

In the specific examples of the charge transporting monomer shown in Tables 1 to 3, Ar, T, j and A² that are present twice in the formula (VI) are respectively the same.

TABLE 1 Structure No. Ar  j  T A²  1

0 CH₂CH₂ OCH₃  2

0 CH₂CH₂ OCH₃  3

0 CH₂CH₂ OCH₃  4

0 CH₂CH₂ OCH₃  5

0 CH₂CH₂ OCH₃  6

1 CH₂CH₂ OCH₃  7

1 CH₂CH₂ OCH₃  8

1 CH₂CH₂ OCH₃  9

1 CH₂CH₂ OCH₃ 10

1 CH₂CH₂ OCH₃

TABLE 2 Structure No. Ar  j  T A² 11

1 CH₂CH₂ OCH₃ 12

1 CH₂CH₂ OCH₃ 13

1 CH₂CH₂ OCH₃ 14

1 CH₂CH₂ OCH₃ 15

1 CH₂CH₂ OCH₃ 16

1 CH₂CH₂ OCH₃ 17

1 CH₂CH₂ OCH₃ 18

1 CH₂CH₂ OCH₃ 19

1 CH₂CH₂ OCH₃ 20

1 CH₂CH₂ OCH₃

TABLE 3 Structure No. Ar  j  T A² 21

1 CH₂CH₂ OCH₃ 22

1 CH₂CH₂ OCH₃ 23

1 CH₂CH₂ OCH₃ 24

1 CH₂CH₂ OCH₃ 25

1 CH₂CH₂ OCH₃ 26

1 CH₂CH₂ OCH₃

Here, first, the method for synthesizing the charge transporting monomer represented by formula (VI) will be described. An example of the method for synthesizing the charge transporting monomer will be shown below, but the method is not limited to this.

As the method for synthesizing the charge transporting monomer (dibenzothiophene compound) represented by the formula (VI), for example, a method using the cross-coupling biaryl synthesis may be mentioned. Specific examples of the cross-coupling biaryl synthesis include, for example, a Suzuki reaction, a Kharasch reaction, a Negishi reaction, a Stille reaction, a Grignard reaction, and an Ullmann reaction.

A specific example of the method for synthesizing the charge transporting monomer represented by formula (VI) may be, for example, a synthesis method based on a cross-coupling reaction between a compound represented by formula (VII) and a compound represented by formula (VIII) as shown in the following formula, but the synthesis method is not limited to this.

In the formula (VII) and formula (VIII), X and G each represent a halogen atom, B(OH)₂, a substituent represented by the following structural formula (X-1), a substituent represented by the following structural formula (X-2), or a substituent represented by the following structural formula (X-3). Furthermore, in the formula (VII) and formula (IX), A², T, j and Ar respectively have the same meanings as A², T, j and Ar in the formula (VI).

Furthermore, during the reaction described above, a metal, a metal complex catalyst, a base, a solvent or the like may also be used as necessary.

Examples of the metal that may be used include palladium (Pd), copper (Cu), titanium (Ti), tin (Sn), nickel (Ni), and platinum (Pt).

Examples of the metal complex that may be used include tetrakis(triphenylphosphine)palladium (Pd(PPh₃)₄), palladium(II) acetate (Pd(OCOCH₃)₂), tris(dibenzylideneacetone)dipalladium(0) (Pd₂(dba)₃), di(triphenylphosphine)dichloropalladium (Pd(PPh₃)₂Cl₂), 1,1′-bis(diphenylphosphino) ferrocene-palladium(II) dichloride-dichloromethane complex (Pd(dppf)₂Cl₂), Pd/C, and nickel(II) acetylacetonate (Ni(acac)₂).

Examples of the base that may be used include inorganic bases such as sodium carbonate (Na₂CO₃), potassium carbonate (K₂CO₃), cesium carbonate (Cs₂CO₃), and barium hydroxide (Ba(OH)₂); and organic bases such as triethylamine (NEt₃), diisopropylamine (NH(i-Pr)₂), diethylamine (NHEt₂), dimethylamine (NHMe₂), trimethylamine (NMe₃), 1,8-diazabicyclo[5.4.0]-7-undecene (DBU), N,N-dimethyl-4-aminopyridine (DMAP), and pyridine.

It is preferable that the solvent be a solvent that does not significantly inhibit the reaction, and examples that may be used include aromatic hydrocarbon solvents such as benzene, toluene, xylene, and mesitylene; ether solvents such as diethyl ether, tetrahydrofuran, and dioxane; acetonitrile, dimethylformamide, dimethyl sulfoxide, methanol, ethanol, isopropyl alcohol, and water.

Furthermore, during the reaction described above, if necessary, for example, triphenylphosphine (PPh₃), tri-o-tolylphosphine (P(o-Tol)₃), tributylphosphine (P(t-Bu)₃), and triethylphosphine (PEt₃) are used.

Meanwhile, Me represents “CH₃”; Et represents “C₂H₅”; Ph represents “C₆H₅”; i-Pr represents “(CH₃)₂CH₂”; o-Tol represents “o-CH₃C₆H₄”; and t-Bu represents “(CH₃)₃C”.

The reaction may be carried out, for example, under normal pressure, in an inert gas atmosphere of nitrogen, argon or the like, but the reaction may also be carried out under pressurized conditions.

The reaction temperature for the reaction may be, for example, in the range of from 20° C. to 300° C., but may also be in the range of from 50° C. to 180° C. The reaction time may vary depending on the reaction conditions, but for example, the reaction time may be selected in the range of from 5 minutes to 20 hours.

The use amount of the metal or metal complex catalyst is not particularly limited, but for example, the use amount may be in the range of from 0.001 mole to 10 moles, or may also be in the range of from 0.01 mole to 5.0 moles, based on one mole of the compound represented by formula (VII).

The use amount of the base may be in the range of from 0.5 mole to 4.0 moles, or may also be in the range of from 1.0 mole to 2.5 moles, based on one mole of the compound represented by formula (VII).

After the reaction described above, for example, the reaction solution is introduced into water, and then the mixture is stirred. When the reaction product is in the form of crystals, a crude product is obtained by collecting the reaction product by suction filtration. When the reaction product is an oily matter, for example, a crude product is obtained by extracting the reaction product with a solvent such as ethyl acetate or toluene. The crude product thus obtained may be purified using a column packed with, for example, silica gel, alumina, activated white clay or activated carbon, or the crude product may also be subjected to a treatment of adsorbing unnecessary components by adding these adsorbents to the solution. Furthermore, if the reaction product is in the form of crystals, the crystals may also be purified by recrystallization from a solvent such as hexane, methanol, acetone, ethanol, ethyl acetate or toluene.

However, the synthesis method according to the exemplary embodiment of the present invention is not intended to be limited to these.

When polymerization is carried out by a known method using the charge transporting monomer represented by the formula (VI) obtained as described above, the charge transporting polyester represented by the formula (I) is synthesized.

Specifically, for example, a method of introducing a substituent that will be described below into the end of the charge transporting monomer (that is, A² in formula (VI)) may be used, and more specifically, the following synthesis method may be employed.

1) In case where A² is a hydroxyl group

The compound represented by the formula (VI) and a divalent alcohol represented by HO—(Y¹—O)_(m)—H are mixed in equal amounts (mass ratio), and the mixture is polymerized using an acid catalyst. Meanwhile, Y¹ and m have the same meanings as Y¹ and m defined for the formula (I).

As the acid catalyst, those conventionally used in ordinary esterification reactions, such as sulfuric acid, toluenesulfonic acid, and trifluoroacetic acid are used, and the acid catalyst is used in an amount of, for example, from 1/10,000 part by mass to 1/10 part by mass, relative to 1 part by mass of the monomer (that is, the compound represented by the formula (VI)). The acid catalyst may also be used in the range of from 1/1,000 part by mass to 1/50 part by mass.

In order to remove water produced during the polymerization, for example, a solvent that is azeotropically boiled with water is used. Specifically, for example, toluene, chlorobenzene, 1-chloronaphthalene and the like are effective, and the solvent is used in an amount in the range of, for example, from 1 part by mass to 100 parts by mass relative to 1 part by mass of the monomer. The solvent may also be used in an amount in the range of from 2 parts by mass to 50 parts by mass.

The reaction temperature is set according to the conditions, but in order to remove the water produced during the polymerization, the reaction may be carried out at the boiling point of the solvent.

After completion of the reaction, if a solvent has not been used, the reaction product is dissolved in a solvent which dissolves the reaction product. If a solvent has been used, the reaction solution may be directly added dropwise into a poor solvent in which a polymer is not easily dissolved, such as an alcohol such as methanol or ethanol, or acetone, to thereby precipitate a polyester. The polyester is separated, subsequently washed with water or an organic solvent, and dried.

Furthermore, if necessary, a reprecipitation treatment of dissolving the reaction product in an appropriate organic solvent, adding the solution dropwise into a poor solvent, and precipitating a polyester may be repeated. At the time of the reprecipitation treatment, the treatment may also be carried out while stirring the system efficiently with a mechanical stirrer or the like. The solvent that dissolves the polyester at the time of the reprecipitation treatment is used in an amount of, for example, from 1 part by mass to 100 parts by mass, relative to 1 part by mass of the polyester, and the solvent may also be used in an amount in the range of from 2 parts by mass to 50 parts by mass. Furthermore, the poor solvent is used in an amount in the range of, for example, from 1 part by mass to 1,000 parts by mass relative to 1 part by mass of the polyester, and may also be used in an amount in the range of from 10 parts by mass to 500 parts by mass.

2) In case where A² is halogen

The compound represented by the formula (VI) and a divalent alcohol represented by HO—(Y¹—O)_(m)—H are mixed in equal amounts (mass ratio), and the mixture is polymerized using an organic basic catalyst such as pyridine or triethylamine. Meanwhile, Y¹ and m described above have the same meanings as Y¹ and m defined for the formula (I).

The organic basic catalyst is used in an amount in the range of, for example, from 1 part by mass to 10 parts by mass relative to 1 part by mass of the monomer, and may also be used in an amount in the range of from 2 parts by mass to 5 parts by mass.

As the solvent, methylene chloride, tetrahydrofuran (THF), toluene, chlorobenzene, 1-chloronaphthalene and the like are effective, and the solvent is used in an amount in the range of, for example, from 1 part by mass to 100 parts by mass relative to 1 part by mass of the monomer (that is, the compound represented by the formula (VI)), and may also be used in an amount in the range of from 2 parts by mass to 50 parts by mass.

The reaction temperature is set according to the conditions. After the polymerization, the reaction product is subjected to a reprecipitation treatment as described above, and is purified.

Furthermore, in the case of using a divalent alcohol having high acidity, such as bisphenol, an interfacial polymerization method may also be used. That is, polymerization is carried out by adding a divalent alcohol to water, adding an equal amount (mass ratio) of a base to dissolve therein, and adding a divalent alcohol and an equal amount of a monomer solution thereto while vigorously stirring the system. At this time, water is used in an amount in the range of, for example, from 1 part by mass to 1,000 parts by mass relative to 1 part by mass of the divalent alcohol, and may also be used in an amount in the range of from 2 parts by mass to 500 parts by mass. As the solvent to dissolve the monomer, methylene chloride, dichloroethane, trichloroethane, toluene, chlorobenzene, 1-chloronaphthalene and the like are effective.

The reaction temperature is set according to the conditions, and in order to accelerate the reaction, it is effective to use a phase transfer catalyst such as an ammonium salt or a sulfonium salt. The phase transfer catalyst is used in an amount of, for example, in the range of from 0.1 part by mass to 10 parts by mass relative to 1 part by mass of the monomer, and may also be used in an amount in the range of from 0.2 part by mass to 5 parts by mass.

3) In case where A² is —O—R⁵

An excess amount of divalent alcohol represented by HO—(Y¹—O)_(m)—H is added to the compound represented by the formula (VI), the mixture is heated using an inorganic acid such as sulfuric acid or phosphoric acid, titanium alkoxide, an acetate or carbonate of calcium, cobalt or the like, or an oxide of zinc or lead as a catalyst, and the product is synthesized by a transesterification reaction. Meanwhile, Y¹ and m have the same meanings as Y¹ and m in the formula (1).

The divalent alcohol is used in an amount in the range of, for example, from 2 parts by mass to 100 parts by mass relative to 1 part by mass of the monomer (compound represented by the formula (VI)), and may also be used in an amount in the range of from 3 parts by mass to 50 parts by mass.

The catalyst is used in an amount in the range of, for example, from 1/10,000 part by mass to 1 part by mass relative to 1 part by mass of the monomer, and may also be used in an amount in the range of from 1/1,000 part by mass to ½ part by mass.

The reaction is carried out at a reaction temperature of from 200° C. to 300° C., and after completion of the transesterification reaction from —O—R⁵ to —O—(Y¹—O)_(m)—H, the reaction is carried out, for example, under reduced pressure in order to accelerate polymerization through the detachment of HO—(Y¹—O)_(m)—H. Furthermore, a high-boiling point solvent such as 1-chloronaphthalene, which azeotropically boils with HO—(Y¹—O)_(m)—H, is used, and the reaction may be carried out while HO—(Y¹—O)_(m)—H is azeotropically removed at normal pressure.

Also, the polyester may also be synthesized as follows.

For each of the cases of items 1) to 3), a compound represented by the following formula (XI) is produced by adding a divalent alcohol in excess and carrying out the reaction, and then this compound is used instead of the monomer represented by the formula (VI) to react with a divalent carboxylic acid, a divalent carboxylic acid halide or the like. Thus, the polyester represented by the formula (I) is obtained.

In the formula (XI), Ar, X, T and j have the same meanings as Ar, X, T and j defined for the formula (II), respectively, and Y¹ and m have the same meanings as Y¹ and m defined for the formula (I), respectively.

Among the synthesis methods of the items 1) to 3), for the charge transporting polyester according to the exemplary embodiment of the present invention, it is easy to carry out the production according to the synthesis method of 1).

Here, specific examples of the charge transporting polyester represented by the formula (I) are shown in Table 4 to Table 6, but the charge transporting polyester according to the exemplary embodiment of the present invention is not limited to these specific examples. Furthermore, in Tables 4 to 6, the number indicated in the column of A¹ of the row of a monomer (column of “Structure of A¹ in formula (I)”) corresponds to the structure number of the specific examples of the structure represented by the formula (II) (“structure number” of the charge transporting monomer in Table 1 to Table 3).

Hereinafter, for each of the specific examples of the charge transporting polyester designated with a compound number (polymer compound number) in the Tables 4 to 6, for example, a specific example designated with the number 15 is referred to as “Exemplary compound (15)”. Furthermore, in each of the specific examples of the charge transporting polyester shown in Tables 4 to 6, Y¹, m and R¹ that are present twice in the formula (I) are respectively the same.

TABLE 4 Struc- Poly- ture of mer A¹ in Com- formula pound (I) Y¹  m  R¹ p  1 1

1 H 55  2 1

1 H 58  3 1

1 H 48  4 1

1 H 65  5 1

1 H 57  6 4

1 H 57  7 4

1 H 38  8 4

1 H 58  9 4

1 H 74 10 6

1 H 80

TABLE 5 Structure Polymer of A¹ in Compound formula (I) Y¹ m R¹ p 11  6

1 H 71 12  7

1 H 67 13  9

1 H 52 14 10

1 H 56 15 12

1 H 69 16 14

1 H 71 17 14

1 H 58 18 15

1 H 49 19 15

1 H 61 20 17

1 H 57

TABLE 6 Poly- Structure mer of A¹ in Com- formula pound (I) Y¹ m R¹ p 21 18

1 H 68 22 19

1 H 68 23 23

1 H 83 24 23

1 H 58 25 24

1 H 68 26 24

1 H 55 27 25

1 H 62 28 26

1 H 59

Next, the configuration of the organic electroluminescent element of the exemplary embodiment of the present invention will be described in detail.

The organic electroluminescent element of the exemplary embodiment of the present invention includes a pair of electrodes, with at least one of the electrodes being transparent or semi-transparent, and one or more organic compound layers interposed between those electrodes, and the layer configuration is not particularly limited as long as at least one layer of the organic compound layers contains one of the charge transporting polyesters described above.

In the organic electroluminescent element of the exemplary embodiment of the present invention, when there is one organic compound layer, the organic compound layer means a light emitting layer having charge transport capability, and the light emitting layer contains the charge transporting polyester. When there are plural organic compound layers (that is, in the case of a functionally separated type with the respective layers having different functions), at least one of the layers becomes a light emitting layer, and this light emitting layer may be a light emitting layer having charge transport capability. In this case, specific examples of the layer configuration including the light emitting layer or a light emitting layer having charge transport capability, and other layers include the following items (1) to (3).

(1) Layer configuration composed of a light emitting layer and at least any one of an electron transport layer and an electron injection layer.

(2) Layer configuration composed of at least any one of a hole transport layer and a hole injection layer, a light emitting layer, and at least any one of an electron transport layer and an electron injection layer.

(3) Layer configuration composed of at least any one of a hole transport layer and a hole injection layer, and a light emitting layer.

The layers other than the light emitting layer, and the light emitting layer having charge transport capability, of these layer configurations (1) to (3) have a function as a charge transport layer or a charge injection layer.

Meanwhile, it is desirable that all of these layer configurations of (1) to (3) contain the charge transporting polyester in any one layer.

Furthermore, in the organic electroluminescent element of the exemplary embodiment, the light emitting layer, the hole transport layer, the hole injection layer, the electron transport layer and the electron injection layer may further contain a charge transporting compound (a hole transporting material or an electron transporting material) other than the charge transporting polyester. The details of the charge transporting compound will be described below.

Hereinafter, the organic electroluminescent element of the exemplary embodiment of the present invention will be described in more detail with reference to drawings, but the organic electroluminescent element is not intended to be limited to these.

FIG. 1 to FIG. 4 are schematic cross-sectional diagrams for explaining the layer configurations of the organic electroluminescent element of the exemplary embodiment of the present invention. FIG. 1, FIG. 2 and FIG. 3 show examples of the case where there are plural organic compound layers, and FIG. 4 shows an example of the case where there is one organic compound layer. Meanwhile, in FIG. 1 to FIG. 4, members having the same function will be described under the same reference numeral.

The organic electroluminescent element shown in FIG. 1 has a configuration in which on a transparent insulator substrate 1, a transparent electrode 2, a light emitting layer 4, at least one layer 5 of an electron transport layer and an electron injection layer, and a back surface electrode 7 are laminated in sequence, and this corresponds to the layer configuration (1). However, when the layer designated with Reference Numeral 5 is composed of an electron transport layer and an electron injection layer, the electron transport layer, the electron injection layer and the back surface electrode 7 are laminated in this order on the back surface electrode 7 side of the light emitting layer 4.

The organic electroluminescent element shown in FIG. 2 has a configuration in which on a transparent insulator substrate 1, a transparent electrode 2, at least one layer 3 of a hole transport layer and a hole injection layer, a light emitting layer 4, at least one layer 5 of an electron transport layer and an electron injection layer, and a back surface electrode 7 are laminated in sequence, and this corresponds to the layer configuration (2). However, when the layer designated with Reference Numeral 3 is constituted of a hole transport layer and a hole injection layer, the hole injection layer, the hole transport layer and the light emitting layer 4 are laminated in this order on the back surface electrode 7 side of the transparent electrode 2. Furthermore, when the layer designated with Reference Numeral 5 is composed of an electron transport layer and an electron injection layer, the electron transport layer, the electron injection layer, and the back surface electrode 7 are laminated in this order on the back surface electrode 7 of the light emitting layer 4.

The organic electroluminescent element shown in FIG. 3 has a configuration in which on a transparent insulator substrate 1, a transparent electrode 2, at least one layer 3 of a hole transport layer and a hole injection layer, a light emitting layer 4 and a back surface electrode 7 are laminated in sequence, and this corresponds to the layer configuration (3). However, when the layer designated with Reference Numeral 3 is composed of a hole transport layer and a hole injection layer, the hole injection layer, the hole transport layer and the light emitting layer 4 are laminated in this order on the back surface electrode 7 side of the transparent electrode 2.

The organic electroluminescent element shown in FIG. 4 has a configuration in which on a transparent insulator substrate 1, a transparent electrode 2, a light emitting layer 6 having charge transport capability, and a back surface electrode 7 are laminated in sequence.

Furthermore, when the organic electroluminescent element has a top emission structure or is made as a transmissive type using transparent electrodes for both the negative electrode and the positive electrode, a structure in which the layer configurations of FIG. 1 to FIG. 4 are stacked in plural stages is also realized.

Hereinafter, each of the configurations will be described in detail.

The charge transporting polyester according to the exemplary embodiment of the present invention is also imparted with any of hole transport capability and electron transport capability through the function of the organic compound layer in which the polyester is included.

For example, in the layer configuration of the organic electroluminescent element shown in FIG. 1, the charge transporting polyester may be included in any one of the light emitting layer 4 and at least one layer 5 of the electron transport layer and the electron injection layer, and acts as all of the light emitting layer 4 and the at least one layer 5 of the electron transport layer and the electron injection layer. Furthermore, in the case of the layer configuration of the organic electroluminescent shown in FIG. 2, the charge transporting polyester may be included in at least one layer 3 of the hole transport layer and the hole injection layer, the light emitting layer 4 and the at least one layer 5 of the electron transport layer and the electron injection layer, and acts as all of the at least one layer 3 of the hole transport layer and the hole injection layer, the light emitting layer 4, and the at least one layer 5 of the electron transport layer and the electron injection layer. Furthermore, in the case of the layer configuration of the organic electroluminescent element shown in FIG. 3, the charge transporting polyester may be included in any one of the at least one layer 3 of the hole transport layer and the hole injection layer, and the light emitting layer 4, and acts as all of the at least one layer 3 of the hole transport layer and the hole injection layer, and the light emitting layer 4. Furthermore, in the case of the layer configuration of the organic electroluminescent element shown in FIG. 4, the charge transporting polyester is included in the light emitting layer 6 having charge transport capability, and acts as the light emitting layer 6 having charge transport capability.

In the case of the layer configurations of the organic electroluminescent element shown in FIG. 1 to FIG. 4, a transparent substrate may be used to extract emitted light for the transparent insulator substrate 1, and a glass plate, a plastic film and the like may be used, but the substrate is not limited to these. The term “transparent” means that the transmittance of light in the visible region is 10% or higher, and the transmittance may be 75% or higher. Hereinafter, the transmittance is equivalent to this value.

Furthermore, the transparent electrode 2 is transparent or semi-transparent so that emitted light is extracted at a level equivalent to that of the transparent insulator substrate, and in order to carry out injection of holes, an electrode having a large work function may be used. An example may be an electrode having a work function of 4 eV or higher. The term “semi-transparent” means that the transmittance of light in the visible region is 70% or higher, and the transmittance may be 80% or higher. Hereinafter, the transmittance is equivalent to this value.

As specific examples, oxide films of indium tin oxide (ITO), tin oxide (NESA), indium oxide, zinc oxide and the like, and deposited or sputtered gold, platinum, palladium and the like are used, but the electrode is not limited to these. The sheet resistance of the electrode is such that a lower value is more desirable, and the sheet resistance may be several hundred Ω/□ or less, or may also be 100Ω/□ or less. The transparent electrode may have a transmittance of light in the visible region of 10% or higher in equivalence to the transparent insulator substrate, and the transmittance may also be 75% or higher.

In the case of the layer configurations of the organic electroluminescent element shown in FIG. 1 to FIG. 3, the electron transport layer or the hole transport layer may be formed from the charge transporting polyester alone, to which a function (electron transport capability or hole transport capability) is imparted according to the purpose. However, for example, in order to regulate the hole mobility, the layer may also be formed by mixing and dispersing a hole transporting material other than the charge transporting polyester in an amount in the range of 0.1% by mass to 50% by mass relative to the total amount of the materials constituting the layer.

Examples of the hole transporting material include a tetraphenylenediamine derivative, a triphenylamine derivative, a carbazole derivative, a stilbene derivative, a spirofluorene derivative, an arylhydrazone derivative, and a porphyrin compound, and among these, examples having good compatibility with the charge transporting polyester include a tetraphenylenediamine derivative, a spirofluorene derivative, and a triphenylamine derivative.

In the case of regulating the electron mobility, the layer may be formed by mixing and dispersing the electron transporting material in an amount of from 0.1% by mass to 50% by mass relative to the total amount of the material constituting the layer.

Examples of the electron transporting material include an oxadiazole derivative, a nitro-substituted fluorenone derivative, a diphenoquinone derivative, a thiopyran dioxide derivative, a silol derivative, a chelate type organometallic complex, a polynuclear or condensed aromatic ring compound, a perylene derivative, a triazole derivative, and a fluorenylidenemethane derivative.

Furthermore, when regulation is required in both the hole mobility and the electron mobility, both the hole transporting material and the electron transporting material may be incorporated together into the charge transporting polyester.

Furthermore, for the purpose of an improvement of the film-forming properties, prevention of pinholes, and the like, an appropriate resin (polymer) and additives may also be added. Specific examples of the resin that may be used include electrically conductive resins such as a polycarbonate resin, a polyester resin, a methacrylic resin, an acrylic resin, a polyvinyl chloride resin, a cellulose resin, a urethane resin, an epoxy resin, a polystyrene resin, a polyvinyl acetate resin, a styrene-butadiene copolymer, a vinylidene chloride-acrylonitrile copolymer, a vinyl chloride-vinyl acetate-maleic anhydride copolymer, a silicone resin, a poly-N-vinylcarbazole resin, a polysilane resin, polythiophene, and polypyrrole. Here, the term conductivity means that, for example, the volume resistivity is in the range of 1.0×10⁹ Ω·cm or less, and the same applies in the following descriptions. Furthermore, as the additives, known antioxidants, ultraviolet absorbents, plasticizers and the like may be used.

Furthermore, in the case of enhancing charge injectability, a hole injection layer or an electron injection layer may be used, and examples of a hole injecting material that may be used include a triphenylamine derivative, a phenylenediamine derivative, a phthalocyanine derivative, an indanthrene derivative, and a polyalkylenedioxythiophene derivative. Furthermore, a Lewis acid, sulfonic acid and the like may be incorporated into these materials. Examples of an electron injecting material that may be used include metals such as lithium (Li), calcium (Ca), barium (Ba), strontium (Sr), silver (Ag) and gold (Au); metal fluorides such as LiF and MgF; and metal oxides such as MgO, Al₂O₃, and LiO.

Furthermore, when the charge transporting polyester is used for a function other than the light emitting function, a luminescent compound is used as the light emitting material. As the light emitting material, a compound that exhibits high light emission quantum efficiency in the solid state is used. The light emitting material may be any of a low molecular weight compound and a polymeric compound, and specific examples of an organic low molecular weight compound include a chelate type organometallic complex, a polynuclear or condensed aromatic ring compound, a perylene derivative, a coumarin derivative, a styrylarylene derivative, a silol derivative, an oxazole derivative, an oxabenzothiazole derivative, an oxathiazole derivative, and an oxadiazole derivative, while specific examples of a polymeric compound that may be used include a polyparaphenylene derivative, a polyparaphenylenevinylene derivative, a polythiophene derivative, and a polyacetylene derivative. Specific examples include the following compounds (XV-1) to (XV-17), but the examples are not limited to these.

Meanwhile, in the structural formulas (XV-13) to (XV-17), V represents the same divalent organic group as Y¹; and n and g each independently represent an integer of 1 or greater.

Furthermore, for the purpose of an enhancement of the durability of the organic electroluminescent element or an enhancement of the light emission efficiency of the element, a dye compound which is different from the light emitting material may be doped as a guest material into the light emitting material or the charge transporting polyester. The proportion of the dye compound doped may be 0.001% by mass to 40% by mass of the object layer, and may also be 0.01% by mass to 10% by mass. As the dye compound used in this doping, an organic compound which has good compatibility with the light emitting material and does not interfere in satisfactory film formation of the light emitting layer is used, and specific examples include a coumarin derivative, a DCM derivative, a quinacridone derivative, a perimidone derivative, a benzopyran derivative, a rhodamine derivative, benzothioxanthene derivative, a rubrene derivative, a porphyrin derivative, and metal complex compounds of ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, gold and the like.

Specific examples of the dye compound include the following compounds (XVI-1) to (XVI-6), but the examples are not limited to these.

Furthermore, the light emitting layer 4 may be formed of the light emitting material alone, but for the purpose of further improving the electrical characteristics and light emitting characteristics, the light emitting layer may be formed by mixing the charge transporting polyester into the light emitting material in an amount in the range of 1% by mass to 50% by mass, and dispersing the mixture. Alternatively, the light emitting layer may be formed by mixing a charge transporting material other than the charge transporting polyester into the light emitting material in an amount in the range of 1% by mass to 50% by mass, and dispersing the mixture. Furthermore, when the charge transporting polyester also has light emitting characteristics, the charge transporting material may also be used as a light emitting material, and in that case, for the purpose of further improving the electrical characteristics and light emitting characteristics, the light emitting layer may be formed by mixing and dispersing a charge transporting material other than the charge transporting polyester in an amount in the range of 1% by mass to 50% by mass.

In the case of the layer configuration of the organic electroluminescent element shown in FIG. 4, the light emitting layer 6 having charge transport capability is an organic compound layer in which a light emitting material (specifically, for example, at least one selected from the light emitting materials (XV-1) to (XV-17)) is dispersed in the charge transporting polyester imparted with a function (hole transport capability or electron transport capability) according to the purpose, in an amount of 50% by mass or less. However, in order to adjust the balance between the holes and electrons injected into the organic electroluminescent element, a charge transporting material other than the charge transporting polyester may be dispersed in an amount of 10% by mass to 50% by mass.

As the charge transporting material, in the case of regulating the electron mobility, examples of the electron transporting material include an oxadiazole derivative, a nitro-substituted fluorenone derivative, a diphenoquinone derivative, a thiopyran dioxide derivative, and a fluorenylidenemethane derivative.

In the case of the layer configurations of the organic electroluminescent element shown in FIG. 1 to FIG. 4, the back surface electrode 7 uses a metal, a metal oxide, a metal fluoride or the like, which all have a small work function in order to be vacuum deposited and perform electron injection. Examples of the metal include magnesium, aluminum, gold, silver, indium, lithium, calcium, and alloys thereof. Examples of the metal oxide include lithium oxide, magnesium oxide, aluminum oxide, indium tin oxide, tin oxide, indium oxide, zinc oxide, and indium zinc oxide. Furthermore, examples of the metal fluoride include lithium fluoride, magnesium fluoride, strontium fluoride, calcium fluoride, and aluminum fluoride.

Furthermore, a protective layer may be further provided on the back surface electrode 7 in order to prevent deterioration of the element due to moisture or oxygen. Specific examples of the material for the protective layer include metals such as In, Sn, Pb, Au, Cu, Ag and Al; metal oxides such as MgO, SiO₂, and TiO₂; and resins such as a polyethylene resin, a polyurea resin, and a polyimide resin. In the formation of the protective layer, a vacuum deposition method, a sputtering method, a plasma polymerization method, a CVD method, or a coating method is applied.

These organic electroluminescent elements shown in these FIG. 1 to FIG. 4 are produced by first sequentially forming individual layers in accordance with each of the layer configurations of the organic electroluminescent element on a transparent electrode 2. The at least one layer 3 of the hole transport layer and the hole injection layer, the light emitting layer 4, the at least one layer 5 of the electron transport layer and the electron injection layer, and the light emitting layer 6 having charge transport capability are formed on a transparent electrode by a vacuum deposition method, or by dissolving or dispersing the respective materials in an appropriate organic solvent, and using the resulting coating liquid by a spin coating method, a casting method, a dipping method, an inkjet method or the like.

The thicknesses of the at least one layer 3 of the hole transport layer and the hole injection layer, the light emitting layer 4, the at least one layer 5 of the electron transport layer and the electron injection layer, and the light emitting layer 6 having charge transport capability may be respectively 10 μm or less, and particularly in the range of from 0.001 μm to 5 μm. The dispersed state of the respective materials (the above-described non-conjugated polymer, light emitting material, and the like) may be a molecular dispersed state or may be a particulate state such as microcrystals. In the case of a film-forming method using a coating liquid, in order to obtain a molecular dispersed state, it is necessary to select the dispersion solvent in consideration of the dispersibility and solubility of the respective materials. In order to disperse the materials in a particulate form, a ball mill, a sand mill, a paint shaker, an attriter, a homogenizer, an ultrasonic method or the like is used.

Finally, in the case of the organic electroluminescent elements shown in FIG. 1 and FIG. 2, the organic electroluminescent element of the exemplary embodiment of the present invention may be obtained by forming the back surface electrode 7 on the at least one layer 5 of the electron transport layer and the electron injection layer by a vacuum deposition method, a sputtering method or the like. Furthermore, in the case of the organic electroluminescent element shown in FIG. 3, the organic electroluminescent element of the exemplary embodiment of the present invention may be obtained by forming the back surface electrode 7 on the light emitting layer 4, and in the case of the organic electroluminescent element shown in FIG. 4, on the light emitting layer 6 having charge transport capability, by a vacuum deposition method, a sputtering method or the like.

<Display Medium>

The display medium of the exemplary embodiment of the present invention is characterized in that the organic electroluminescent element of the exemplary embodiment of the present invention is arranged in at least one of a matrix form and a segment form. In the case of arranging the organic electroluminescent element in a matrix form in the exemplary embodiment, only the electrodes may be arranged in the matrix form, or both the electrodes and the organic compound layer may be arranged in the matrix form. Furthermore, in the case of arranging the organic electroluminescent element in a segment form in the exemplary embodiment, only the electrodes may be arranged in the segment form, or both the electrodes and the organic compound layer may be arranged in the segment form.

The organic compound layer in the matrix form or the segment form is easily formed by, for example, using the inkjet method described above.

As the driving apparatus for a display medium constituted of the organic electroluminescent element arranged in a matrix form and the organic electroluminescent element arranged in the segment form, and the method for driving the driving apparatus, the conventionally known ones are used.

EXAMPLES

Hereinafter, the present invention will be described more specifically with Examples. However, the present invention is not intended to be limited to these Examples.

<Synthesis of Charge Transporting Polyester>

Synthesis Example 1 Synthesis of Exemplary Compound (10)

Acetanilide (25.0 g), methyl 4-iodophenylpropionate (64.4 g), potassium carbonate (38.3 g), copper sulfate pentahydrate (2.3 g), and n-tridecane (50 ml) are introduced into a 500-ml three-necked flask, and the mixture is heated and stirred at 230° C. for 20 hours under a nitrogen gas stream.

After completion of the reaction, potassium hydroxide (15.6 g) dissolved in ethylene glycol (300 ml) is added thereto, and the resulting mixture is heated to reflux for 3.5 hours under a nitrogen gas stream, and then is cooled to room temperature (25° C.). The reaction liquid is poured into 1 L of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. The crystals are filtered by suction filtration, and washed with water, and then the crystals are transferred to a 1-L flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently a methanol (300 ml) solution of concentrated sulfuric acid (1.5 ml) is added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

After the reaction, extraction is carried out with toluene, and the organic layer is washed with pure water. Subsequently, the organic layer is dried over anhydrous sodium sulfate, the solvent is distilled off under reduced pressure, and recrystallization from hexane is carried out. Thus, 36.5 g of DAA-1 shown below is obtained.

Subsequently, a liquid mixture of 1-bromo-4-iodobenzene (5.3 g), DAA-1 (5.0 g), copper (II) sulfate pentahydrate (0.2 g), potassium carbonate (1.3 g), and tridecane (10 ml) is stirred for 6 hours at 210° C.

After completion of the reaction, potassium hydroxide (15.6 g) dissolved in ethylene glycol (300 ml) is added to the liquid mixture, and the resulting mixture is heated to reflux for 3.5 hours under a nitrogen gas stream, and then is cooled to room temperature (25° C.). The reaction liquid is poured into 1 L of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. The crystals are filtered by suction filtration, and washed with water, and then the crystals are transferred to a 1-L flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently a methanol (300 ml) solution of concentrated sulfuric acid (1.5 ml) is added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

The reaction mixture is cooled to room temperature (25° C.), toluene is added thereto, and the mixture is filtered through Celite. The filtrate is washed with pure water, and the organic layer is extracted. A product obtained by distilling off the organic solvent of the organic layer is separated by silica gel column chromatography (hexane 4:toluene 1), and thus 4.5 g of TAA-1 is obtained.

Subsequently, in a 500-ml three-necked flask, a 30% aqueous solution of hydrogen peroxide (34.0 g) is added dropwise to a mixture of dibenzothiophene (18.4 g) and acetic acid (200 ml) over 20 minutes, and the resulting mixture is magnetically stirred for 9 hours at 90° C.

After completion of the reaction, the reaction mixture is introduced into an ice bath (600 ml), and extraction is carried out with chloroform (800 ml). The organic layer is washed sequentially with water (200 ml), a saturated aqueous solution of iron sulfate (80 ml), 10% sodium carbonate (100 ml), water (200 ml), and saturated brine (200 ml), and is dried over calcium chloride. The organic solvent is distilled off, and colorless crystals are obtained. These crystals are recrystallized (150 ml of chloroform, and 200 ml of ethanol), and thus 18.2 g of dibenzothiophene dioxide is obtained.

In a 500-ml three-necked flask, dibenzothiophene dioxide (18 g) is dissolved in sulfuric acid (250 ml), and N-bromosuccinimide (29.6 g) is added thereto. The mixture is stirred for 18 hours at room temperature (25° C.), and then the reaction solution is slowly introduced into ice water (800 ml). A precipitate deposited is suction filtered, washed with water (200 ml), a 10% aqueous solution of NaOH (100 ml) and water (200 ml), and dried over calcium chloride. The product is recrystallized from chloroform (700 ml), and thus 20.1 g of 3,7-dibromodibenzothiophene dioxide is obtained.

Lithium aluminum hydride (4.1 g) is slowly introduced in small amounts over 50 minutes, in an ice bath, into a mixture of 3,7-dibromodibenzothiophene dioxide (20 g) and anhydrous ether (200 ml) in a 500-ml flask, and the mixture is heated to reflux and stirred for 2 hours. Water (200 ml) is added thereto to deactivate lithium aluminum hydride, and chloroform (200 ml) and concentrated hydrochloric acid (40 ml) are added to the mixture. The resulting mixture is thoroughly stirred, and the organic layer is separated. The aqueous layer is further extracted with chloroform (200 ml×2), and the extract is combined with the organic layer. The combined organic layer is washed with water (200 ml) and saturated brine (200 ml), and is dried over calcium chloride. The solvent is distilled off, and colorless crystals thus obtained are recrystallized from ethyl acetate+ethanol (16:3). Thus, 8.8 g of 3,7-dibromodibenzothiophene is obtained.

Under a nitrogen atmosphere, 3,7-dibromodibenzothiophene (8 g) is introduced into a 500-ml flask, and anhydrous tetrahydrofuran (200 ml) is added thereto to dissolve the compound. The solution is cooled to −78° C. 1.5 M tert-butyllithium (37.8 ml) is slowly added dropwise thereto over 20 minutes, and the mixture is magnetically stirred for 6 hours at −78° C. Triisopropyl borate (31.2 ml) is introduced into the mixture all at one time, and the resulting mixture is magnetically stirred for 0.5 hour at −78° C. and is further magnetically stirred for one hour at room temperature (25° C.) The mixture is cooled to −78° C., and 1 M hydrochloric acid (100 ml) is introduced thereto all at one time. Thereafter, the mixture is magnetically stirred for one hour at room temperature (25° C.). Tetrahydrofuran is distilled off, and a precipitate deposited therein is suction filtered and dissolved in a 5% aqueous KOH solution (100 ml). 1 M hydrochloric acid is added to this solution, and a precipitate deposited therein is suction filtered. This precipitate is dissolved in tetrahydrofuran (300 ml), and 2,2-dimethyl-1,3-propanediol (4.5 g), sodium sulfate, and a molecular sieve powder are added to the solution to dry the solution. The solvent is distilled off, and colorless crystals thus obtained are recrystallized from hexane+ethyl acetate. Thus, 4.9 g of a diboronic acid compound is obtained.

Under a nitrogen atmosphere, tetrahydrofuran (250 ml) is added to tetra(triphenylphosphine)palladium (0.54 g) and TAA-1 (8.1 g) in a 500-ml flask, and the mixture is stirred for 10 minutes. Subsequently, a 2 N aqueous solution of sodium carbonate (24.5 ml) and the diboronic acid compound (2.00 g) are added to the mixture, and the resulting mixture is heated to reflux and magnetically stirred for 7 hours.

After completion of the reaction, ethyl acetate (100 ml) and water (50 ml) are added to the reaction mixture, and the mixture is thoroughly stirred. Thus, an organic layer and an aqueous layer are separated. The aqueous layer is extracted with ethyl acetate (100 ml), and the respective organic layers are washed with saturated brine (100 ml) and dried over sodium sulfate. The dried product is subjected to separation by silica gel column chromatography (ethyl acetate/hexane=1/3), and thus, 1.2 g of a monomer compound (6) is obtained.

1.0 g of the monomer compound (6) thus obtained, 10 ml of ethylene glycol and 0.02 g of tetrabutoxytitanium are introduced into a 50-ml three-necked pear-shaped flask, and the mixture is heated and stirred at 200° C. for 5 hours in a nitrogen atmosphere.

It is confirmed by TLC that the raw material monomer compound (6) has reacted and disappeared, and then, while ethylene glycol is distilled off under reduced pressure at 50 Pa, the reaction mixture is heated to 210° C. and is allowed to react continuously for 6 hours.

Thereafter, the reaction mixture is cooled to room temperature (25° C.) and is dissolved in 50 ml of tetrahydrofuran The insoluble matter is filtered through a 0.5-μm polytetrafluoroethylene (PTFE) filter, and the filtrate is distilled off under reduced pressure. The residue is dissolved in 300 ml of monochlorobenzene, and the solution is washed with 300 ml of 1 N-HCl and 500 ml×3 of water in this order. The monochlorobenzene solution is distilled off under reduced pressure to a final volume of 30 ml, and the concentrated solution is added dropwise to 800 ml of ethyl acetate/methanol=1/3 to reprecipitate the polymer. The polymer thus obtained is filtered, washed with methanol, and then dried in a vacuum at 60° C. for 16 hours. Thus, 0.6 g of the polymer [Exemplary Compound (10)] is obtained.

The molecular weight of this polymer is measured by gel permeation chromatography (GPC) (manufactured by Tosoh Corp., HLC-8120 GPC), and the weight average molecular weight is Mw=6.7×10⁴ (relative to styrene standards), Mw/Mn=2.2, and the degree of polymerization p determined from the molecular weight of the monomer is about 80.

Synthesis Example 2 Synthesis of Exemplary Compound (12)

4-Methylacetanilide (21.0 g), methyl 4-iodophenylpropionate (64.4 g), potassium carbonate (38.3 g), copper sulfate pentahydrate (2.3 g), and tridecane (50 ml) are introduced into a 500-ml three-necked flask, and the mixture is heated and stirred at 230° C. for 15 hours under a nitrogen gas stream.

After completion of the reaction, potassium hydroxide (15.6 g) dissolved in ethylene glycol (300 ml) is added thereto, and the resulting mixture is heated to reflux for 3.5 hours under a nitrogen gas stream and then cooled to room temperature (25° C.). The reaction liquid is poured into 1 L of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. The crystals are filtered by suction filtration, and washed with water, and then the crystals are transferred to a 1-L flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently a methanol (300 ml) solution of concentrated sulfuric acid (1.5 ml) is added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

After the reaction, extraction is carried out with toluene, and the organic layer is washed with pure water. Subsequently, the organic layer is dried over anhydrous sodium sulfate, subsequently the solvent is distilled off under reduced pressure, and recrystallization from hexane is carried out. Thus, 34.1 g of DAA-2 shown below is obtained.

Subsequently, a liquid mixture of 1-bromo-4-iodobenzene (15.8 g), DAA-2 (15.0 g), copper(II) sulfate pentahydrate (0.7 g), potassium carbonate (3.9 g), and tridecane (10 ml) is stirred for 12 hours at 210° C.

After completion of the reaction, potassium hydroxide (15.6 g) dissolved in ethylene glycol (300 ml) is added to the liquid mixture, and the resulting mixture is heated to reflux for 3.5 hours under a nitrogen gas stream, and then is cooled to room temperature (25° C.). The reaction liquid is poured into 1 L of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. The crystals are filtered by suction filtration, and washed with water, and then the crystals are transferred to a 1-L flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently a methanol (300 ml) solution of concentrated sulfuric acid (1.5 ml) is added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

The reaction mixture is cooled to room temperature (25° C.), toluene is added thereto, and the mixture is filtered through Celite. The filtrate is washed with pure water, and the organic layer is extracted. A product obtained by distilling off the organic solvent of the organic layer is separated by silica gel column chromatography (hexane 4:toluene 1), and thus 9.3 g of TAA-2 is obtained.

In a nitrogen atmosphere, tetrahydrofuran (300 ml) is added to tetra(triphenylphosphine)palladium (0.54 g) and TAA-2 (8.5 g) in a 500-ml flask, and the mixture is stirred for 10 minutes. Subsequently, a 2 M aqueous solution of sodium carbonate (24.5 ml) and the diboronic acid compound (2.00 g) are added to the mixture, and the resulting mixture is heated to reflux and magnetically stirred for 7 hours.

After completion of the reaction, ethyl acetate (100 ml) and water (50 ml) are added to the reaction mixture, and the resulting mixture is thoroughly stirred. Thus, an organic layer and an aqueous layer are separated. The aqueous layer is extracted with ethyl acetate (100 ml), and the respective organic layers are washed with saturated brine (100 ml) and dried over sodium sulfate. The organic layer is separated by silica gel column chromatography (ethyl acetate/hexane=1/3), and thus 1.1 g of a monomer compound (7) is obtained.

1.0 g of the monomer compound (7) thus obtained, 10 ml of ethylene glycol and 0.02 g of tetrabutoxytitanium are introduced into a 50-ml three-necked pear-shaped flask, and the mixture is heated and stirred for 5 hours at 200° C. in a nitrogen atmosphere.

It is confirmed by TLC that the monomer compound (7), which is a raw material, has reacted and disappeared, and then, while ethylene glycol is distilled off under reduced pressure at 50 Pa, the system is heated to 210° C. and is allowed to react continuously for 6 hours.

Thereafter, the reaction mixture is cooled to room temperature (25° C.) and is dissolved in 50 ml of tetrahydrofuran. The insoluble matter is filtered through a 0.5-μm polytetrafluoroethylene (PTFE) filter, and the filtrate is distilled off under reduced pressure. The residue is dissolved in 300 ml of monochlorobenzene, and the solution is washed with 300 ml of 1 N-HCl and 500 ml×3 of water in this order. The monochlorobenzene solution is distilled off under reduced pressure to a final volume of 30 ml, and the concentrated solution is added dropwise to 800 ml of ethyl acetate/methanol=1/3 to reprecipitate the polymer. The polymer thus obtained is filtered, washed with methanol, and then dried in a vacuum at 60° C. for 16 hours. Thus, 0.7 g of the polymer [Exemplary Compound (12)] is obtained.

The molecular weight of this polymer is measured by gel permeation chromatography (GPC) (manufactured by Tosoh Corp., HLC-8120 GPC), and the weight average molecular weight is Mw=5.8×10⁴ (relative to styrene standards), Mw/Mn=2.3, and the degree of polymerization p determined from the molecular weight of the monomer is about 67.

Synthesis Example 3 Synthesis of Exemplary Compound (20)

1-Acetamidonaphthalene (25.0 g), methyl 4-iodophenylpropionate (64.4 g), potassium carbonate (38.3 g), copper sulfate pentahydrate (2.3 g), and tridecane (50 ml) are introduced into a 500-ml three-necked flask, and the mixture is heated and stirred at 230° C. for 18 hours under a nitrogen gas stream.

After completion of the reaction, potassium hydroxide (15.6 g) dissolved in ethylene glycol (300 ml) is added thereto, and the resulting mixture is heated to reflux for 3.5 hours under a nitrogen gas stream and then cooled to room temperature (25° C.). The reaction liquid is poured into 1 L of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. The crystals are filtered by suction filtration, and washed with water, and then the crystals are transferred to a 1-L flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently a methanol (300 ml) solution of concentrated sulfuric acid (1.5 ml) is added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

After the reaction, extraction is carried out with toluene, and the organic layer is washed with pure water. Subsequently, the organic layer is dried over anhydrous sodium sulfate, subsequently the solvent is distilled off under reduced pressure, and recrystallization from hexane is carried out. Thus, 36.5 g of DAA-3 is obtained.

Subsequently, a liquid mixture of 1-bromo-4-iodobenzene (21.2 g), DAA-3 (20 g), copper(II) sulfate pentahydrate (1.0 g), potassium carbonate (5.0 g) and tridecane (12 ml) is stirred for 14 hours at 210° C.

After completion of the reaction, potassium hydroxide (15.6 g) dissolved in ethylene glycol (300 ml) is added to the reaction mixture, and the resulting mixture is heated to reflux for 3.5 hours under a nitrogen gas stream and then cooled to room temperature (25° C.). The reaction liquid is poured into 1 L of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. The crystals are filtered by suction filtration, and washed with water, and then the crystals are transferred to a 1-L, flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently a methanol (300 ml) solution of concentrated sulfuric acid (1.5 ml) is added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

The reaction mixture is cooled to room temperature (25° C.), toluene is added thereto, and the mixture is filtered through Celite. The filtrate is washed with pure water, and the organic layer is extracted. The organic solvent is distilled off, and the product thus obtained is separated by silica gel column chromatography (hexane 4:toluene 1). Thus, 14.5 g of TAA-3 is obtained.

In a nitrogen atmosphere, tetrahydrofuran (300 ml) is added to tetra(triphenylphosphine)palladium (0.537 g) and TAA-3 (8.8 g) in a 500-ml flask, and the mixture is stirred for 8 minutes. Subsequently, a 2 M aqueous solution of sodium carbonate (24.5 ml) and diboronic compound 11 (2.00 g) are added thereto, and the mixture is heated to reflux and magnetically stirred for 7 hours.

After completion of the reaction, ethyl acetate (100 ml) and water (50 ml) are added to the reaction mixture, and the resulting mixture is thoroughly stirred. Thus, an organic layer and an aqueous layer are separated. The aqueous layer is extracted with ethyl acetate (100 ml), and the respective organic layers are washed with saturated brine (100 ml) and dried over sodium sulfate. The organic layer is separated by silica gel column chromatography (ethyl acetate/hexane=1/3), and thus 1.4 g of a monomer compound (17) is obtained.

1.0 g of the monomer compound (17) thus obtained, 10 ml of ethylene glycol and 0.02 g of tetrabutoxytitanium are introduced into a 50-ml three-necked pear-shaped flask, and the mixture is heated and stirred for 5 hours at 200° C. in a nitrogen atmosphere.

It is confirmed by TLC that the monomer compound (17), which is a raw material, has reacted and disappeared, and then, while ethylene glycol is distilled off under reduced pressure at 50 Pa, the system is heated to 210° C. and is allowed to react continuously for 6 hours.

Thereafter, the reaction mixture is cooled to room temperature (25° C.) and is dissolved in 50 ml of tetrahydrofuran. The insoluble matter is filtered through a 0.5-μm polytetrafluoroethylene (PTFE) filter, and the filtrate is distilled off under reduced pressure. The residue is dissolved in 300 ml of monochlorobenzene, and the solution is washed with 300 ml of 1 N-HCl and 500 ml×3 of water in this order. The monochlorobenzene solution is distilled off under reduced pressure to a final volume of 30 ml, and the concentrated solution is added dropwise to 800 ml of ethyl acetate/methanol=1/3 to reprecipitate the polymer. The polymer thus obtained is filtered, washed with methanol, and then dried in a vacuum at 60° C. for 16 hours. Thus, 0.6 g of the polymer [Exemplary Compound (20)] is obtained.

The molecular weight of this polymer is measured by gel permeation chromatography (GPC) (manufactured by Tosoh Corp., HLC-8120 GPC), and the weight average molecular weight is Mw=5.3×10⁴ (relative to styrene standards), Mw/Mn=2.4, and the degree of polymerization p determined from the molecular weight of the monomer is about 57.

Synthesis Example 4 Synthesis of Exemplary Compound (22)

4-(2-Thienyl)acetanilide (30.0 g), methyl. 4-iodophenylpropionate (28.5 g), potassium carbonate (13.6 g), copper sulfate pentahydrate (2.0 g), and 1,2-dichlorobenzene (50 ml) are introduced into a 500-ml three-necked flask, and the mixture is heated and stirred at 230° C. for 12 hours under a nitrogen gas stream.

After completion of the reaction, potassium hydroxide (15.6 g) dissolved in ethylene glycol (300 ml) is added thereto, and the resulting mixture is heated to reflux for 3.5 hours under a nitrogen gas stream and then cooled to room temperature (25° C.). The reaction liquid is poured into 1 L of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. The crystals are filtered by suction filtration, and washed with water, and then the crystals are transferred to a 1-L flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently a methanol (300 ml) solution of concentrated sulfuric acid (1.5 ml) is added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

After the reaction, extraction is carried out with toluene, and the organic layer is washed with pure water. Subsequently, the organic layer is dried over anhydrous sodium sulfate, subsequently the solvent is distilled off under reduced pressure, and recrystallization from hexane is carried out. Thus, 17.9 g of DAA-4 is obtained.

In a nitrogen atmosphere, a liquid mixture of 1-bromo-4-iodobenzene (15.9 g), DAA-4 (16.0 g), copper (II) sulfate pentahydrate (0.2 g), potassium carbonate (1.3 g) and tridecane (15 ml) is stirred for 15 hours at 210° C.

After completion of the reaction, potassium hydroxide (15.6 g) dissolved in ethylene glycol (300 ml) is added thereto, and the resulting mixture is heated to reflux for 3.5 hours under a nitrogen gas stream and then cooled to room temperature (25° C.). The reaction liquid is poured into 1 L of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. The crystals are filtered by suction filtration, and washed with water, and then the crystals are transferred to a 1-L flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently a methanol (300 ml) solution of concentrated sulfuric acid (1.5 ml) is added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

After cooling, toluene is added to the reaction mixture, and the mixture is filtered through Celite. Toluene is distilled off, and the product thus obtained is separated by silica gel column chromatography (hexane 2:toluene 1). Thus, 9.1 g of TAA-4 is obtained.

In a nitrogen atmosphere, tetrahydrofuran (250 ml) is added to tetra(triphenylphosphine)palladium (0.54 g) and TAA-4 (8.6 g) in a 500-ml flask, and the mixture is stirred for 10 minutes. Subsequently, a 2 M aqueous solution of sodium carbonate (24.5 ml) and the diboronic acid compound (2.00 g) are added to the mixture, and the resulting mixture is heated to reflux and magnetically stirred for 7 hours.

After completion of the reaction, ethyl acetate (100 ml) and water (50 ml) are added to the reaction mixture, and the mixture is thoroughly stirred. Thus, an organic layer and an aqueous layer are separated. The aqueous layer is extracted with ethyl acetate (100 ml), and the respective organic layers are washed with saturated brine (100 ml), and dried over sodium sulfate. The dried product is separated by silica gel column chromatography (ethyl acetate/hexane=1/3), and thus 1.2 g of a monomer compound (19) is obtained.

1.0 g of the monomer compound (19) thus obtained, 10 ml of ethylene glycol and 0.02 g of tetrabutoxytitanium are introduced into a 50-ml three-necked pear-shaped flask, and the mixture is heated and stirred for 5 hours at 200° C. in a nitrogen atmosphere.

It is confirmed by TLC that the raw material monomer compound (19) has reacted and disappeared, and then, while ethylene glycol is distilled off under reduced pressure at 50 Pa, the reaction mixture is heated to 210° C. and is allowed to react continuously for 6 hours.

Thereafter, the reaction mixture is cooled to room temperature (25° C.) and is dissolved in 50 ml of tetrahydrofuran. The insoluble matter is filtered through a 0.5-μm polytetrafluoroethylene (PTFE) filter, and the filtrate is distilled off under reduced pressure. The residue is dissolved in 300 ml of monochlorobenzene, and the solution is washed with 300 ml of 1 N-HCl and 500 ml×3 of water in this order. The monochlorobenzene solution is distilled off under reduced pressure to a final volume of 30 ml, and the concentrated solution is added dropwise to 800 ml of ethyl acetate/methanol=1/3 to reprecipitate the polymer. The polymer thus obtained is filtered, washed with methanol, and then dried in a vacuum at 60° C. for 16 hours. Thus, 0.6 g of the polymer [Exemplary Compound (22)] is obtained.

The molecular weight of this polymer is measured by gel permeation chromatography (GPC) (manufactured by Tosoh Corp., HLC-8120 GPC), and the weight average molecular weight is Mw=6.8×10⁴ (relative to styrene standards), Mw/Mn=2.1, and the degree of polymerization p determined from the molecular weight of the monomer is about 68.

Synthesis Example 5 Synthesis of Exemplary Compound (23)

In a nitrogen atmosphere, 2-iodo-9,9-dimethylfluorene (31.8 g), methyl 4-acetaminophenylpropionate (20.0 g), potassium carbonate (18.8 g), copper sulfate pentahydrate (1.2 g), and tridecane (15 ml) are introduced into a 300-ml three-necked flask, and the mixture is heated and stirred at 200° C. for 13 hours under a nitrogen gas stream.

After completion of the reaction, ethylene glycol (150 ml) and potassium hydroxide (7.6 g) are added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream and then cooled to room temperature (25° C.). The cooled product is poured into 150 ml of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. These crystals are filtered and washed with water, and then the crystals are transferred to a 500-ml flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently methanol (100 ml) and concentrated sulfuric acid (1.0 ml) are added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

After the reaction, extraction is carried out with toluene, and the organic layer is washed with distilled water. Subsequently, the organic layer is dried over anhydrous sodium sulfate, subsequently the solvent is distilled off under reduced pressure, and recrystallization from hexane is carried out. Thus, 25 g of DAA-5 is obtained.

Subsequently, a liquid mixture of 1-bromo-4-iodobenzene (21.2 g), DAA-5 (20 g), copper (II) sulfate pentahydrate (1.0 g), potassium carbonate (4.5 g) and tridecane (10 ml) is stirred for 8 hours at 210° C.

After completion of the reaction, ethylene glycol (150 ml) and potassium hydroxide (7.6 g) are added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream and then cooled to room temperature (25° C.). The cooled product is poured into 150 ml of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. These crystals are filtered and washed with water, and then the crystals are transferred to a 500-ml flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently methanol (100 ml) and concentrated sulfuric acid (1.0 ml) are added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

The reaction mixture is cooled to room temperature (25° C.), toluene is added thereto, and the mixture is filtered through Celite. The filtrate is washed with pure water, and the organic layer is extracted. The organic solvent is distilled off, and a product thus obtained is separated by silica gel column chromatography (hexane 4:toluene 1). Thus, 15.6 g of TAA-5 is obtained.

In a nitrogen atmosphere, tetrahydrofuran (250 ml) is added to tetra(triphenylphosphine)palladium (0.54 g) and TAA-5 (8.8 g) in a 500-ml flask, and the mixture is stirred for 10 minutes. Subsequently, a 2 M aqueous solution of sodium carbonate (24.5 ml) and the diboronic acid compound (2.00 g) are added to the mixture, and the resulting mixture is heated to reflux and magnetically stirred for 7 hours.

After completion of the reaction, ethyl acetate (100 ml) and water (50 ml) are added to the reaction mixture, and the mixture is thoroughly stirred. Thus, an organic layer and an aqueous layer are separated. The aqueous layer is extracted with ethyl acetate (100 ml), and the respective organic layers are washed with saturated brine (100 ml), and dried over sodium sulfate. The dried product is separated by silica gel column chromatography (ethyl acetate/hexane=1/3), and thus 1.2 g of a monomer compound (23) is obtained.

1.0 g of the monomer compound (23) thus obtained, 10 ml of ethylene glycol and 0.02 g of tetrabutoxytitanium are introduced into a 50-ml three-necked pear-shaped flask, and the mixture is heated and stirred for 5 hours at 200° C. in a nitrogen atmosphere.

It is confirmed by TLC that the raw material monomer compound (23) has reacted and disappeared, and then, while ethylene glycol is distilled off under reduced pressure at 50 Pa, the reaction mixture is heated to 210° C. and is allowed to react continuously for 6 hours.

Thereafter, the reaction mixture is cooled to room temperature (25° C.) and is dissolved in 50 ml of tetrahydrofuran. The insoluble matter is filtered through a 0.5-μm polytetrafluoroethylene (PTFE) filter, and the filtrate is distilled off under reduced pressure. The residue is dissolved in 300 ml of monochlorobenzene, and the solution is washed with 300 ml of 1 N-HCl and 500 ml×3 of water in this order. The monochlorobenzene solution is distilled off under reduced pressure to a final volume of 30 ml, and the concentrated solution is added dropwise to 800 ml of ethyl acetate/methanol=1/3 to reprecipitate the polymer. The polymer thus obtained is filtered, washed with methanol, and then dried in a vacuum at 60° C. for 16 hours. Thus, 0.6 g of the polymer [Exemplary Compound (23)] is obtained.

The molecular weight of this polymer is measured by gel permeation chromatography (GPC) (manufactured by Tosoh Corp., HLC-8120 GPC), and the weight average molecular weight is Mw=8.9×10⁴ (relative to styrene standards), Mw/Mn=2.4, and the degree of polymerization p determined from the molecular weight of the monomer is about 83.

Synthesis Example 6 Synthesis of Exemplary Compound (18)

In a nitrogen atmosphere, 3-bromobiphenyl (23 g), methyl 4-acetaminophenylpropionate (20 g), potassium carbonate (18.8 g), copper sulfate pentahydrate (1.1 g), and tridecane (20 ml) are introduced into a 300-ml three-necked flask, and the mixture is heated and stirred at 200° C. for 24 hours under a nitrogen gas stream.

After completion of this reaction, ethylene glycol (150 ml) and potassium hydroxide (6.5 g) are added thereto, and the resulting mixture is heated to reflux for 3 hours under a nitrogen gas stream and then cooled to room temperature (25° C.). The cooled product is poured into 150 ml of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. These crystals are filtered and washed with water, and then the crystals are transferred to a 500-ml flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently methanol (100 ml) and concentrated sulfuric acid (1.0 ml) are added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

After the reaction, extraction is carried out with toluene, and the organic layer is washed with distilled water. Subsequently, the organic layer is dried over anhydrous sodium sulfate, subsequently the solvent is distilled off under reduced pressure, and recrystallization from hexane is carried out. Thus, 25 g of DAA-6 is obtained.

Subsequently, a liquid mixture of 1-bromo-4-iodobenzene (15.9 g), DAA-6 (15 g), copper(II) sulfate pentahydrate (0.6 g), potassium carbonate (3.9 g) and tridecane (10 ml) is stirred for 10 hours at 210° C.

After completion of the reaction, ethylene glycol (150 ml) and potassium hydroxide (6.5 g) are added thereto, and the resulting mixture is heated to reflux for 3 hours under a nitrogen gas stream and then cooled to room temperature (25° C.). The cooled product is poured into 150 ml of distilled water and neutralized with hydrochloric acid, and crystals are precipitated out. These crystals are filtered and washed with water, and then the crystals are transferred to a 500-ml flask. Toluene (500 ml) is added to this, and the mixture is heated to reflux. Water is removed by azeotropically boiling the reaction mixture, subsequently methanol (100 ml) and concentrated sulfuric acid (1.0 ml) are added thereto, and the resulting mixture is heated to reflux for 5 hours under a nitrogen gas stream.

The reaction mixture is cooled to room temperature (25° C.), toluene is added thereto, and the mixture is filtered through Celite. The filtrate is washed with pure water, and the organic layer is extracted. The organic solvent is distilled off, and a product thus obtained is separated by silica gel column chromatography (hexane 4:toluene 1). Thus, 11.7 g of TAA-6 is obtained.

In a nitrogen atmosphere, tetrahydrofuran (250 ml) is added to tetra(triphenylphosphine)palladium (0.54 g) and TAA-6 (8.6 g) in a 500-ml flask, and the mixture is stirred for 10 minutes. Subsequently, a 2 M aqueous solution of sodium carbonate (24.5 ml) and the diboronic acid compound (2.00 g) are added to the mixture, and the resulting mixture is heated to reflux and magnetically stirred for 7 hours.

After completion of the reaction, ethyl acetate (100 ml) and water (50 ml) are added to the reaction mixture, and the mixture is thoroughly stirred. Thus, an organic layer and an aqueous layer are separated. The aqueous layer is extracted with ethyl acetate (100 ml), and the respective organic layers are washed with saturated brine (100 ml), and dried over sodium sulfate. The dried product is separated by silica gel column chromatography (ethyl acetate/hexane=1/3), and thus 1.2 g of a monomer compound (15) is obtained.

1.0 g of the monomer compound (15) thus obtained, 10 ml of ethylene glycol and 0.02 g of tetrabutoxytitanium are introduced into a 50-ml three-necked pear-shaped flask, and the mixture is heated and stirred for 5 hours at 200° C. in a nitrogen atmosphere.

It is confirmed by TLC that the raw material monomer compound (15) has reacted and disappeared, and then, while ethylene glycol is distilled off under reduced pressure at 50 Pa, the reaction mixture is heated to 210° C. and is allowed to react continuously for 6 hours.

Thereafter, the reaction mixture is cooled to room temperature (25° C.) and is dissolved in 50 ml of tetrahydrofuran. The insoluble matter is filtered through a 0.5-μm polytetrafluoroethylene (PTFE) filter, and the filtrate is distilled off under reduced pressure. The residue is dissolved in 300 ml of monochlorobenzene, and the solution is washed with 300 ml of 1 N-HCl and 500 ml×3 of water in this order. The monochlorobenzene solution is distilled off under reduced pressure to a final volume of 30 ml, and the concentrated solution is added dropwise to 800 ml of ethyl acetate/methanol=1/3 to reprecipitate the polymer. The polymer thus obtained is filtered, washed with methanol, and then dried in a vacuum at 60° C. for 16 hours. Thus, 0.6 g of the polymer [Exemplary Compound (18)] is obtained.

The molecular weight of this polymer is measured by gel permeation chromatography (GPC) (manufactured by Tosoh Corp., HLC-8120 GPC), and the weight average molecular weight is Mw=4.9×10⁴ (relative to styrene standards), Mw/Mn=2.2, and the degree of polymerization p determined from the molecular weight of the monomer is about 49.

Example 1

ITO (manufactured by Sanyo Vacuum Industries Co., Ltd.) formed on a transparent insulating substrate is subjected to patterning by photolithography using a strip-shaped photomask, and the ITO is further subjected to an etching treatment. Thereby, a strip-shaped ITO electrode (width 2 mm) is formed. Subsequently, this ITO glass substrate is washed with a neutral detergent, ultrapure water, acetone (electronic grade, manufactured by Kanto Chemical Co., Inc.) and isopropanol (electronic grade, manufactured by Kanto Chemical Co., Inc.) while applying ultrasonic waves for 5 minutes for each, and then the ITO glass substrate is dried with a spin coater.

A 5% by mass monochlorobenzene solution of the charge transporting polyester [Exemplary Compound (10)] is prepared, the solution is filtered through a 0.2-μm PTFE filter, and then a thin film having a thickness of 0.050 μm of this solution is formed, as a hole transport layer, on the above-described substrate by a spin coating method. The Exemplary Compound (XV-1) is deposited as a light emitting material, and a light emitting layer having a thickness of 0.055 μm is formed. Subsequently, a metallic mask provided with strip-shaped holes is provided thereon, and then LiF is deposited to a thickness of 0.0001 μm. Subsequently, Al is deposited to a thickness of 0.150 μm, and then a back surface electrode having a width of 2 mm and a thickness of 0.15 μm is formed so as to intersect with the ITO electrode. The effective area of the organic electroluminescent element thus formed is 0.04 cm².

Example 2

A 10% by mass dichloroethane solution of 1 part by mass of the charge transporting polyester [Exemplary Compound (12)], 4 parts by mass of poly (N-vinylcarbazole) and 0.02 part by mass of the Exemplary Compound (XV-1) is prepared, and the solution is filtered through a 0.2-μm PTFE filter. On a glass substrate on which a strip-shaped ITO electrode has been etched, washed and dried in the same manner as in Example 1, a thin film having a thickness of 0.15 μm is formed using the above solution by a spin coating method. After the thin film is sufficiently dried, LiF is deposited to a thickness of 0.0001 μm by installing a metal mask provided with strip-shaped holes. Subsequently, Al is deposited to a thickness of 0.150 μm, and a back surface electrode having a width of 2 mm and a thickness of 0.15 μm is formed so as to intersect with the ITO electrode. The effective area of the organic electroluminescent element thus formed is 0.04 cm².

Example 3

On an ITO glass substrate which has been etched, washed and dried in the same manner as in Example 1, a layer having a thickness of 0.050 μm is formed, as a hole transport layer, using the charge transporting polyester [Exemplary Compound (20)] in the same manner as in Example 1. Subsequently, a mixture of the Exemplary Compound (XV-1) and the Exemplary Compound (XVI-1) (mass ratio: 99/1) is used to form a layer having a thickness of 0.065 μm as a light emitting layer. As an electron transport layer, the Exemplary Compound (XV-9) is used to form a layer having a thickness of 0.030 μm. After the layers are sufficiently dried, LiF is deposited to a thickness of 0.0001 μm by installing a metal mask provided with strip-shaped holes. Subsequently, Al is deposited to a thickness of 0.150 μm, and a back surface electrode having a width of 2 mm and a thickness of 0.15 μm is formed so as to intersect with the ITO electrode. The effective area of the organic electroluminescent element thus formed is 0.04 cm².

Example 4

On an ITO glass substrate which has been etched, washed and dried in the same manner as in Example 1, a layer having a thickness of 0.050 μm is formed, as a hole transport layer, by an inkjet method (a piezoinkjet system) using the charge transporting polyester [Exemplary Compound (22)] in the same manner as in Example 1. Subsequently, as a light emitting layer, a layer of the Exemplary Compound (XV-16, n=8) containing 5% by mass of the Exemplary Compound (XVI-5) is formed to a thickness of 0.065 μm by a spin coating method. After the layers are sufficiently dried, Ca is deposited to a thickness of 0.08 μm, Al is deposited to a thickness of 0.15 μm, and a back surface electrode having a width of 2 mm and a thickness of 0.23 μm is formed so as to intersect with the ITO electrode. The effective area of the organic electroluminescent element thus formed is 0.04 cm².

Example 5

An organic electroluminescent element is produced in the same manner as in Example 2, except that the charge transporting polyester [Exemplary Compound (23)] is used instead of the charge transporting polyester [Exemplary compound (10)] used in Example 1.

Example 6

An organic electroluminescent element is produced in the same manner as in Example 3, except that the charge transporting polyester [Exemplary Compound (18)] is used instead of the charge transporting polyester [Exemplary Compound (10)] used in Example 1.

Example 7

A 1.5% by mass dichloroethane solution of a charge transporting polyester [Exemplary Compound (10)] is prepared, and the solution is filtered through a 0.2-μm PTFE filter. On an ITO glass substrate which has been etched, washed and dried in the same manner as in Example 1, a thin film having a thickness of 0.05 μm is formed by an inkjet method using the above solution. Subsequently, the Exemplary Compound (XV-16, n 8) containing 5% by mass of the Exemplary Compound (XVI-5) is used as a light emitting material to form a light emitting layer to a thickness of 0.050 μm by a spin coating method. After the layers are sufficiently dried, Ca is deposited to a thickness of 0.08 μm, Al is deposited to a thickness of 0.15 μm, and a back surface electrode having a width of 2 mm and a thickness of 0.23 μm is formed so as to intersect with the ITO electrode. The effective area of the organic electroluminescent element thus formed is 0.04 cm².

Example 8

On an ITO glass substrate which has been etched, washed and dried in the same manner as in Example 1, a layer of the Exemplary Compound (XV-16) is formed as a light emitting layer to a thickness of 0.050 μl. A 1.5% by mass dichloroethane solution of the charge transporting polyester [Exemplary Compound (10)] is prepared, and the solution is filtered through a 0.2-μm PTFE filter. This solution is used to form an electron transport layer having a thickness of 0.015 μm formed on the light emitting layer by a spin coating method. After the layers are sufficiently dried, LiF is deposited to a thickness of 0.0001 μm using a metal mask provided with strip-shaped holes, Al is deposited to a thickness of 0.150 μm, and a back surface electrode having a width of 2 mm and a thickness of 0.15 μm is formed so as to intersect with the ITO electrode. The effective area of the organic electroluminescent element thus formed is 0.04 cm².

Comparative Example 1

An organic EL element is produce in the same manner as in Example 2, except that a compound represented by the following structural formula (XVII) is used instead of the charge transporting polyester [Exemplary Compound (10)] used in Example 1.

Comparative Example 2

Two parts by mass of polyvinylcarbazole (PVK) as a charge transporting polymer, 0.1 part by mass of the Exemplary Compound (XV-1) as a light emitting material, and 1 part by mass of the Exemplary Compound (XV-9) as an electron transporting material are mixed to prepare a 10% by mass dichloroethane solution, and the solution is filtered through a 0.2-μm PTFE filter. On a glass substrate on which a strip-shaped ITO electrode having a width of 2 mm is formed by etching, a hole transport layer having a thickness of 0.15 μm is formed by applying the above solution by a dipping method. After the layers are sufficiently dried, LiF is deposited to a thickness of 0.0001 μm using a metal mask provided with strip-shaped holes, subsequently Al is deposited to a thickness of 0.150 μm and a back surface electrode having a width of 2 mm and a thickness of 0.15 μm is formed so as to intersect with the ITO electrode. The effective area of the organic electroluminescent element thus formed is 0.04 cm².

Comparative Example 3

Two parts by mass of a compound having a structure represented by the following structural formula (XVIII) as a charge transporting polymer, 0.1 part by mass of the Exemplary Compound (XV-1) as a light emitting material, and 1 part by mass of the compound (XV-9) as an electron transporting material are mixed to prepare a 10% by mass dichloroethane solution, and the solution is filtered through a 0.1-μm PTFE filter. On a glass substrate on which a strip-shaped ITO electrode having a width of 2 mm is formed by etching, a hole transport layer having a thickness of 0.15 μm is formed by applying the above solution by a dipping method. After the layers are sufficiently dried, LiF is deposited to a thickness of 0.0001 μm using a metal mask provided with strip-shaped holes, subsequently Al is deposited to a thickness of 0.150 μm, and a back surface electrode having a width of 2 mm and a thickness of 0.15 μm is formed so as to intersect with the ITO electrode. The effective area of the organic electroluminescent element thus formed is 0.04 cm².

Comparative Example 4

An organic EL element is produced in the same manner as in Example 1, except that a compound having a structure represented by the following structural formula (XIX) is used instead of the charge transporting polyester [Exemplary. Compound (10)] used in Example 1.

For the organic EL elements produced as described above, a direct current voltage is applied in dry nitrogen by connecting the ITO electrode side as a positive electrode and the back surface electrode as a negative electrode, and measurements are made.

The evaluation of luminescence lifetime is carried out by setting the initial luminance to 1000 cd/m² in a direct current driving system (DC driving) at room temperature (25° C.), and determining the relative time when the driving time at the time point at which the luminance of the element of Comparative Example 1 (initial luminance L₀: 1000 cd/m²) reaches luminance L/initial luminance L₀=0.5, is designated as 1.0, and the voltage increment (=voltage/initial driving voltage) at the time point at which the luminance of the element reaches luminance L/initial luminance L₀=0.5. The results are shown in Table 7.

TABLE 7 Voltage increase Relative time (@L/L₀ = 0.5) (L/L₀ = 0.5) Example 1 1.18 1.75 Example 2 1.12 1.48 Example 3 1.16 1.58 Example 4 1.15 1.62 Example 5 1.14 1.58 Example 6 1.12 1.49 Example 7 1.11 1.55 Example 8 1.15 1.58 Comparative Example 1 1.41 1.00 Comparative Example 2 1.26 1.15 Comparative Example 3 1.35 1.20 Comparative Example 4 1.25 1.32

From the results shown in Table 7, it is understood that in the organic electroluminescent elements of Examples 1 to 8 using the charge transporting polyester according to the exemplary embodiment of the present invention, an increase in voltage is suppressed, and the luminescence lifetime is better than those using the conventional charge transporting polymers.

Furthermore, at is understood that in the organic electroluminescent elements according to the exemplary embodiment of the present invention, since the charge transporting polyester exhibits solubility in organic solvents, large-area organic electroluminescent elements can be easily produced.

The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents. 

1. An organic electroluminescent element comprising: a pair of electrodes including a positive electrode and a negative electrode, with at least one of the electrodes being transparent or semi-transparent; and one or more organic compound layers interposed between the pair of electrodes, with at least one layer containing one or more charge transporting polyesters represented by the following formula (I):

wherein in the formula (I), A¹ represents at least one selected from structures represented by the following formula (II); Y¹s each independently represent a substituted or unsubstituted divalent hydrocarbon group; m's each independently represent an integer of from 1 to 5; p represents an integer of from 5 to 5,000; R¹s each independently represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group;

wherein in the formula (II), Ar's each independently represent a substituted or unsubstituted phenyl group, a substituted or unsubstituted monovalent polynuclear aromatic hydrocarbon group having two aromatic rings, a substituted or unsubstituted monovalent condensed aromatic hydrocarbon group having two or three aromatic rings, or a substituted or unsubstituted monovalent aromatic heterocyclic group; j's each independently represent 0 or 1; T's each independently represent a divalent linear hydrocarbon group having from 1 to 6 carbon atoms, or a divalent branched hydrocarbon group having from 2 to 10 carbon atoms; and X represents a group represented by the following formula (III):


2. The organic electroluminescent element of claim 1, wherein the organic compound layers include a light emitting layer and at least one layer of an electron transport layer and an electron injection layer, and at least one layer selected from the light emitting layer, the electron transport layer and the electron injection layer contains one or more charge transporting polyesters represented by the formula (I).
 3. The organic electroluminescent element of claim 1, wherein the organic compound layers include a light emitting layer and at least one layer of a hole transport layer and a hole injection layer, and at least one layer selected from the light emitting layer, the hole transport layer and the hole injection layer contains one or more charge transporting polyesters represented by the formula (I).
 4. The organic electroluminescent element of claim 1, wherein the organic compound layers include a light emitting layer, at least one layer of a hole transport layer and a hole injection layer, and at least one layer of an electron transport layer and an electron injection layer, and at least one layer selected from the light emitting layer, the hole transport layer, the hole injection layer, the electron transport layer and the electron injection layer contains one or more charge transporting polyesters represented by the formula (I).
 5. The organic electroluminescent element of claim 1, wherein the organic compound layers are formed only of a light emitting layer having a charge transport function, and the light emitting layer having a charge transport function contains one or more charge transporting polyesters represented by the formula (I).
 6. A display medium comprising the organic electroluminescent element of claim 1 arranged in at least one of a matrix form and a segment form.
 7. A display medium comprising the organic electroluminescent element of claim 2 arranged in at least one of a matrix form and a segment form.
 8. A display medium comprising the organic electroluminescent element of claim 3 arranged in at least one of a matrix form and a segment form. 